Modeling Comparisons to Plasma Observations Obtained from RPI/IMAGE

Phillip A. Webb
NAS/NRC/Goddard Space Flight Center 
Code 692
Greenbelt 
Maryland 20771
USA

Robert F Benson
NASA/Goddard Space Flight Center Code 692
Greenbelt 
Maryland 20771
USA

Bodo W Reinisch
University of Massachusetts Lowell
Lowell
Massachusetts 01854
USA

NASA's Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite (J. L. Burch,
EOS, Trans. AGU, 82, 241 and 245, 2001) is currently in a highly inclined elliptical orbit 
that takes it between altitudes of 1000 km and seven Earth radii. During each 14.2 hour 
orbit IMAGE's instruments have the opportunity to observe the plasma distribution from the 
topside ionosphere to beyond the plasmapause. One such instrument carried by IMAGE is the 
Radio Plasma Imager (RPI) (B. W. Reinisch et al., Geophys. Res. Lett., 28, 1167-1170, 2001). 
Using the RPI, the local electron density can be separately calculated from observed plasma 
resonances and the plasma spectrograms. An electron density profile for each orbit can be 
obtained by calculating the electron density at different points along the orbit, which can 
then be compared to the predictions of plasmaspheric electron density models.  

Several static empirical models of the plasmasphere have been published.  Two such models 
are the Carpenter and Anderson ISEE/whistler based model (D. L. Carpenter and R. R. Anderson, 
J. Geophys. Res.}, 97, 1097-1108, 1992), and the GCPM model (D. L. Gallagher et al., 
J. Geophys. Res., 105, 18819-18833, 2000). The theoretical based Global Plasmasphere 
Ionosphere Density (GPID) model has recently been developed by the first author to simulate 
the global scale evolution of the number densities of the ions and electrons in the 
plasmasphere. Combined with the latest version of the International Reference Ionosphere 
(IRI), GPID can model the dynamic emptying caused by geomagnetic storms and the following 
refilling of the plasmasphere. 

The accuracy of the empirical models and the theoretical GPID model will be ascertained by 
comparing their predictions with the electron densities derived from the RPI by conducting 
these comparisons across a variety of geomagnetic L-shells and various geomagnetic storm 
conditions.

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To be presented at the January 2002 URSI meeting, Boulder, Colorado